1. Field of the Invention
The invention relates to temperature compensation attenuators for compensating temperature characteristics of high frequency or microwave devices and systems used in electronics and communication. The attenuators can be applied in various circuits and systems utilizing high frequency waves or microwaves, and more particularly, are suitable for use in mobile communication systems, satellite communication systems, satellite navigational systems, and radar systems which require strict temperature characteristics.
2. Description of the Related Art
Temperature compensation attenuators are widely used in RF circuits. To obtain temperature compensation attenuators with good RF performance, discrete components used in the temperature compensation attenuators should be as small as possible. This causes inconvenience and difficulties during production. Moreover, high operating temperature often results in detachment of small discrete components, which negatively affects reliability of the attenuators. In addition, due to the fact that a film thermistor (NTC) with a high temperature coefficient and low resistance covers a large area on the base (substrate), it is often desirable to reduce the number of devices used in an attenuator. This would result in a temperature compensation attenuator with a wide temperature variation range. Increasing the number of film resistors will greatly increase production difficulty. Moreover, a thermistor connected in parallel with a general resistor features a smaller temperature variation range compared to a single thermistor structure having the same size and amount of material.